Electrolytic cell cleaning apparatus



Dec. 20, 19.55

J. c. BAKER 2,72 7,788

ELECTROLYTIC CELL CLEANING APPARATUS Filed July 3, 1951 FIG. 2

INVENTOR. JOSE C. BAKER United States Patent ELECTROLYTIC CELL CLEANINGAPPARATUS Jose Charlton Baker, Pasadena, Tex assignor to Diamond Alkali(Iompany, Cleveland, Ohio, a corporation of Delaware Application July 3,1951, Serial No. 235,059

2 Claims. (Cl. 299-141) This invention relates to electrolytic cellsparticularly for the electrolysis of sodium chloride brine to obtainchlorine and caustic soda therefrom and has a special relation to suchcells of the diaphragm-cathode type, though, as will be clear to thoseskilled in the art, is has application in other similar apparatus. Itmore particularly relates to the maintenance and rebuilding of cathodesof such electrolytic cells. An especially useful application of theinvention is in application to diaphragm-type electrolytic cells of thegeneral type of those illustrated in K. E. Stuart Patent No. 1,866,065.

Cells of the type of the Stuart patent mentioned above are characterizedby having alternate anodes and cathodes mounted as closely as possiblewithin a minimum cell area. Economy of space and avoidance of greatsolution distances for electrolysis are both considerations in closearrangement of anodes and cathodes. The anodes of such cells arecustomarily of solid carbon and, as in the cell referred to in theaforesaid patent, may be mounted in the base of the cell upon which aliquid-tight, cathode-supporting frame is mounted.

The cathodes of such a cell, on the other hand, comprise foraminousscreens over which are laid materials providing a filter surface whichpermits the passage of ions therethrough but inhibits the passage ofliquid from the anolyte to the catholyte chamber. A common method offorming such cathodes is to spread asbestos paper sheet over the entirecathode surface. Another common and extremely commercially successfulmethod is to deposit such asbestos diaphragm upon the foraminous cathodescreens. This depositing technique is also the development of K. E.Stuart, as is described in his Patent Nos. 1,855,497, 1,862,244, and1,865,152. Upon completion of the depositing technique, a screen ofasbestos fibers is deposited upon the foraminous cathode screen over theentire surface thereof, and the cathode frame is then ready to beassembled with the anodes already mounted in the base of the cell tocomplete the entire electrolytic cell.

Such an electrolytic cell for treating saturated brine to obtaintherefrom chlorine and caustic soda may last in use for a period from afew weeks to many, many months. At the conclusion of that time, eitherdue to erosion of anodes or much more likely due to packing of thefilter media whereby the desired flow through the cathode is impeded,some rebuilding and repairing will be necessary in order to restore thecell to its original efliciency. It has been found, of course, that itis not desirable to discard the entire cathode screen merely because theasbestos portion thereof has become too tightly matted to permit passageof the desired liquids therethrough at an efiicient rate. 0n the otherhand, the asbestos itself apparently is not susceptible to anyreasonable treatment for renewal thereof but, on the contrary, must hecompletely removed from the metallic screen cathode and either thecathode rewrapped with asbestos paper or the deposition procedure, asdescribed in the aforesaid Stuart patents, carried out again on a cleanscreen.

It has been found, and the problem is a serious one where a large numberof cells is being operated in a single operation, that the removal ofasbestos paper which has been wrapped upon such foraminous screening orthe removal of asbestos deposited upon such surfaces many months beforerepresents a very substantial technical problem, especially after thecell has been on the line for a period of many months. When oneconsiders that new anodes are seldom over 1% inches thick, that thespace between cell elements is kept as low as possible, say /2 inch, butthat such cell elements may be several feet long and a foot or so high,it will be appreciated that the problem of mechanically attaching eachindividual cathode screen over its entire area to remove therefrom allold asbestos (since any old asbestos left on the structure contributesto initial and continued inefiiciency in the newly rebuilt cell) is asubstantial one. Heretofore, the only known means for removing suchasbestos from the forraminous cathode screens was to scrape the sametherefrom by hand or with the assistance of water injected between thecathodes themselves, which gave some assistance in the removal problem.In any case, however, the removal problem was one of very heavy laborcosts, Whereby the cell rebuilding job was made considerably moreexpensive than it should have been merely for the purpose of renewingthe diaphragm on the cathode screens.

The present invention contemplates a device for removing asbestos,either sheet or deposited, from such screen material of cathodes ofelectrolytic cells, which device may be used for general filter cleaningpurposes in similar circumstances as that encountered in cells of thetype described in Patent No. 1,866,065. In addition, the presentinvention is directed to a method of removing old asbestos from usedcathode structures, which method results in substantial labor savingsover previous methods practiced in the art and, therefore, results inputting the cells back on the line, producing chlorine and caustic sodaor other materials, as the case may be, much sooner than has been thecase in the past.

It is an object of the present invention to provide a device for theremoval of old filter material from foraminous screens and other filtersupport structures.

It is a further object of the invention to provide a device particularlyadapted for the removal of diaphragms from cathode structures of cells,especially those cells adapted for the production of chlorine andcaustic soda, and particularly cells wherein alternate cathodes andanodes are set up in relatively close association, as in Patent No.1,866,065.

A. further object of the invention is to provide an improved method foruse in the rebuilding of electrolytic cells for the production ofchlorine and caustic soda, which method represents very substantialsavings over and above the methods practiced in the prior art forrebuilding such cells.

Other and further objects of the present invention will become apparentas the description of a preferred embodiment thereof proceeds. Suchpreferred embodiment is described in the following portion of thespecification and includes the drawing in which Fig. 1 is an elevationof a structure embodying the present invention, and

Pig. 2 is an end section of the structure of Fig. 1 taken on the line 22of Fig. 1 but showing the structure in position between a pair ofcathodes to be treated.

Referring to the drawings, Fig. 1 shows the device including handle 12,which may suitably have threads 14 for attachment of a source of water(not shown) at high pressure. Depending upon the size of theelectrolytic cell involved, handle 12 may be of considerable length,such as, as much as 36 or 48 inches. Handle 12 has extension 16 which issuitably provided with narrow slots 18 and otherwise is water-tight. Asmay be seen particul'arlyfrom Fig.2, slot 18 permits the ejection ofwater therethrough directly against the sides of the cathodes 20 fromwhich'it is desired to remove the old cathode diaphragm material. I Aparticular advantage of the present structure is to benoted in therelatively rectangular shape of the actual spray portion of the deviceshown as extension 16 and particularly clearly illustrated in Fig. 2.Thus, water coming out of slot 18 at high pressure impinges directlyagainst the asbestos layer 22 on the forarninous screen 24 and, inwashing away the asbestos, has but relatively constricted space betweenthe walls of the cathode and the walls of the extension 16, wherebyrelatively high pressure is maintained at that point to force theasbestos or other filter material away from the screen 24.

Itwill be appreciated that with this device, it is necessary only toinsert the same between a pair of cathodes in order to remove therefromall of the old asbestos material or other filter material depositedthereupon, whereby no hand work in cleaning the foraminous screens orother filter surfaces is necessary. Moreover, in one form of theinvention, wherein the diagonal of the extension 16 is longer than thedistance between two screens 24, it is a preferred step in practicingthe method of the invention to turn the extension 16 until its cornerscontact the screen, whereby the high pressure water from slots 18 hitsthe cathodes tangentially and thus the removal of asbestos 22 isfacilitated.

It has been found in actual practice that this apparatus and methodprovide a very substantial saving in rebuilding of cells, so that at thepresent time, employing the device of the present invention and themethod hereof, a multiple cathode structure which heretofore requiredmany hours to clean by hand, can quite simply, with high pressure waterand the present invention, be completely cleaned in a matter of a fewminutes.

While there have been described various embodiments of the invention,the apparatus described is not intended to be understood as limiting thescope of the invention as it is realized that changes therewithin arepossible and it is further intended that each element recited in any ofthe following claims is to be understood as referring to all equivalentelements for accomplishing substantially the same results insubstantially the same or equivalent manner, it being intended to coverthe invention broadly in whatever form its principle may be utilized.

What is claimed is:

1. A device for removing used diaphragms from foraminous cathodes ofelectrolytic cells, including a handle, a closed-end, tubular member ofsubstantially rectangular cross-section secured to and extending fromsaid handle, said tubular member having narrow slots in oppositelydisposed walls thereof, said rectangular cross-section having a diagonalgreater than the distance between said foraminous cathodes, said slotsextending longitudinally substantially parallel to the longitudinal axisof said tubular member, and means connected to said tubular member forintroducing fluid under pressure thereinto.

2. A cleaning device for removing filter material simultaneously fromtwo spaced planar foraminous surfaces, said device comprising a handle,a hollow, substantially rectangular member secured to said handle at oneend and closed at the other, said hollow member having oppositelydisposed substantially planar sides, only two of said sides each havinga slot therethrough extending linearly in a direction substantiallyparallel to the longitudinal axis of said handle, said sides defining aconstruction small enough to pass freely between said foraminoussurfaces while the distance between opposite corners of saidcross-section is greater than the distance between said foraminoussurfaces, thereby to permit oscillatory movement of said hollow memberabout the longitudinal axis of said handle between two foraminoussurfaces to facilitate cleaning thereof, but not rotary motion aboutsaid longitudinal axis between said foraminous surfaces, and means forintroducing fluid under pressure into said hollow member.

References Cited in the file of this patent UNITED STATES PATENTS1,186,226 Parker June 6, 1916 1,521,390 Reynolds Dec. 30, 1924 1,635,115Deutsch July 5, 1927 1,644,226 Bedard Oct. 4, 1927 1,743,953 Beatty Jan.14, 1930 1,768,314 Folta June 24, 1930 1,783,237 Greer Dec. 2, 19301,923,828 Janota Aug. 22, 1933 2,064,072 McArdle Dec. 15, 1936 2,081,168Mering May 25, 1937 2,345,808 Green Apr. 4, 1944 2,581,781 Ahlfors Jan.8, 1952 FOREIGN PATENTS 28,415 Austria May 10, 1907

1. A DEVICE FOR REMOVING USED DIAPHRAGMS FROM FORAMINOUS CATHODES OFELECTROLYTIC CELLS, INCLUDING A HANDLE A CLOSED-END, TUBULAR MEMBER OFSUBSTANTIALLY RECTANGULAR CROSS-SECTION SECURED TO AND EXTENDING FROMSAID HANDLE, SAID TUBULAR MEMBER HAVING NARROW SLOTS IN OPPOSITELYDISPOSED WALLS THEREOF, SAID RECTANGULAR CROSS-SECTION HAVING A DIAGONALGREATER THAN THE DISTANCE BETWEEN SAID FORAMINOUS CATHODES, SAID SLOTSEXTENDING LONGITUDINALLY SUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXISOF SAID TUBULAR MEMBER, AND MEANS CONNECTED TO SAID TUBULAR MEMBER FORINTRODUCING FLUID UNDER PRESSURE THEREINTO.